Cognitive decline and dementia represent very important public health problems that impact the ability to maintain social function and independent living. The aim of this study was to investigate the effects of a nonpharmacological intervention consisting of comprehensive cognitive training in elderly people having one of three different cognitive statuses. In all, 321 elderly people with a diagnoses of mild–moderate Alzheimer's disease (AD), with mild cognitive impairment (MCI) and without cognitive decline were randomly assigned to two groups: experimental group (EG, who underwent intervention) and control group (CG), according to a prospective randomized intervention study. In the three groups, immediately after the end of the intervention, we observed a significant effect on some cognitive and noncognitive outcomes in the EGs. At the end of the intervention, we found an intermediate intervention effect on the Alzheimer's Disease Assessment Scale (ADAS) score of subjects with AD, as well as on functional status, as measured by using the Instrumental Activities of Daily Living scale. A significant intervention effect was also observed on enhancement of auditory verbal short-term memory and subjective memory complaints of subjects with MCI. The group of subjects without cognitive decline obtained a significant intervention effect on subjective complaints outcomes. The obtained results demonstrated that participation in the intervention could improve performance with respect to specific cognitive functions and psychological statuses. The role of healthy lifestyle programs, such as the use of comprehensive interventions, has been shown to be efficient for enhancing memory and other abilities in aged individuals with and without cognitive decline.